1. Field of the Invention
The present invention relates to a chemically amplified positive resist composition used in fine processing of semiconductors, a component resin in the composition, a (meth)acrylic derivative for the component resin and a process for producing the (meth)acrylic derivative.
2. Related Art
Semiconductor microfabrication employs a lithography process using a resist composition. In lithography, theoretically, the shorter the exposure wavelength becomes, the higher the resolution can be made, as expressed by Rayleigh's diffraction limit formula. The wavelength of an exposure light source for lithography used in the manufacture of semiconductor devices has been shortened year by year as g line having a wavelength of 436 nm, i line having a wavelength of 365 nm, KrF excimer laser having a wavelength of 248 nm and ArF excimer laser having a wavelength of 193 nm. F2 excimer laser having a wavelength of 157 nm seems to be the next-generation exposure light source. Further, as the exposure light source of the subsequent generation, soft X ray (EUV) having a wavelength of 13 nm or shorter has been proposed as the exposure light source following the 157 nm-wavelength F2 excimer laser.
As line width has become narrower in lithography process using light sources having shorter wavelength, such as excimer laser and the like, especially line edge roughness (roughness of pattern surfaces or wave of pattern, abbreviated by LER), as well as resolution, sensitivity and pattern shape, has become important subject (e.g. Proc. of SPIE Vol. 5038 (2003), 689-698).
After forming patterns by application of the resist composition, exposure of light, and development, there exists a technique adding a step narrowing width of hollows and diameter of holes to make patterns finer by high temperature baking to swell the resist (e.g. JP-A-H09-213603). Hereinafter, the step described above may be referred to as “Reflow Step”.
With further advance of microfabrication technology, it is required for new photoresist compositions to show more advantageous abilities than conventional photoresists. Specifically, photoresist compositions giving better resolution, sensitivity, pattern profiles to resist pattern obtained therefrom, especially giving better line edge roughness are required. Under certain circumstances, further, photoresist compositions capable of giving finer patterns by Reflow Step are required.